All chlorophyll (Chl)-binding proteins involved in photosynthesis of higher plants are hydrophobic membrane proteins integrated into the thylakoids. However, a different category of Chl-binding proteins, the so-called water-soluble Chl proteins (WSCPs), was found in members of the Brassicaceae, Polygonaceae, Chenopodiaceae, and Amaranthaceae families. WSCPs from different plant species bind Chl a and Chl b in different ratios. Some members of the WSCP family are induced after drought and heat stress as well as leaf detachment. It has been proposed that this group of proteins might have a physiological function in the Chl degradation pathway. We demonstrate here that a protein that shared sequence homology to WSCPs accumulated in etiolated barley (Hordeum vulgare) seedlings exposed to light for 2 h. The novel 22-kD protein was attached to the outer envelope of barley etiochloroplasts, and import of the 27-kD precursor was light dependent and induced after feeding the isolated plastids the tetrapyrrole precursor 5-aminolevulinic acid. HPLC analyses and spectroscopic pigment measurements of acetone-extracted pigments showed that the 22-kD protein is complexed with chlorophyllide. We propose a novel role of WSCPs as pigment carriers operating during light-induced chloroplast development.In light-grown seedlings and mature green plants, chlorophyll (Chl) a and Chl b as well as carotenoids are bound to various proteins within PSI and PSII (Ort and Yocum, 1996). These proteins differ in their Chlbinding properties: one group binds only Chl a, whereas the other can bind both Chl a and Chl b (for reviews, see von Wettstein et al., 1995;Green and Durnford, 1996). The first group is represented by the plastid-encoded pigment-binding proteins of the actual reaction centers (PSI-A/B and D1/D2 in PSII) and the photosynthetic cores of PSII (CP43 and CP47).The second group comprises the light-harvesting Chl a/b-binding proteins LHCI and LHCII of PSI and PSII, respectively (Dreyfuss and Thornber, 1994;Kü hlbrandt et al., 1994;Green and Durnford, 1996). These nuclear gene products form the outer antenna complexes of the two photosystems. The Chl content of LHCII accounts for approximately 50% of all Chls in the thylakoid membranes (Kü hlbrandt et al., 1994). LHCII operates as a trimer (Dreyfuss and Thornber, 1994), and each monomer contains Chl a plus Chl b in a 7:6 stoichiometry (Kü hlbrandt et al., 1994). Monomeric LHCII is embedded into the thylakoids via three a-helices (Kü hlbrandt et al., 1994). Similar, structurally related a-helices also occur in other Chl-binding proteins, such as the minor light-harvesting Chl a/bbinding proteins CP29, CP26, CP24, and CP14 (summarized in Green et al., 1991;Jansson, 1994; Paulsen, 1995), and the early light-inducible proteins (ELIPs; Kloppstech et al., 1984;Grimm and Kloppstech, 1987;Grimm et al., 1989; for review, see Adamska, 1997). The S-subunit of PSII (PsbS) is a related but four-helix Chl-binding protein, which contains an additional fourth helix similar to helix 2 present in LHC...

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This review takes an approach to implanted medical devices that considers whether the intention of the implanted device is to have any communication of energy or materials with the body. The first part describes some specific examples of three different classes of implants, analyzed with regards to the type of signal sent to cells. Through several examples, the authors describe that a one way signaling to the body leads to encapsulation or degradation. In most cases, those phenomena do not lead to major problems. However, encapsulation or degradation are critical for new kinds of medical devices capable of duplex communication, which are defined in this review as symbiotic devices. The concept the authors propose is that implanted medical devices that need to be symbiotic with the body also need to be designed with an intended duplex communication of energy and materials with the body. This extends the definition of a biocompatible system to one that requires stable exchange of materials between the implanted device and the body. Having this novel concept in mind will guide research in a new field between medical implant and regenerative medicine to create actual symbiotic devices.

The goal of this study was to determine whether the Tethapod system, which was designed to determine the impedance properties of lipid bilayers, could be used for cell culture in order to utilise micro-impedance spectroscopy to examine further biological applications. To that purpose we have used normal epithelial cells from kidney (RPTEC) and a kidney cancer cell model (786-O). We demonstrate that the Tethapod system is compatible with the culture of 10,000 cells seeded to grow on a small area gold measurement electrode for several days without affecting the cell viability. Furthermore, the range of frequencies for EIS measurements were tuned to examine easily the characteristics of the cell monolayer. We demonstrate significant differences in the paracellular resistance pathway between normal and cancer kidney epithelial cells. Thus, we conclude that this device has advantages for the study of cultured cells that include (i) the configuration of measurement and reference electrodes across a microfluidic channel, and (ii) the small surface area of 6 parallel measurement electrodes (2.1 mm2) integrated in a microfluidic system. These characteristics might improve micro-impedance spectroscopy measurement techniques to provide a simple tool for further studies in the field of the patho-physiology of biological barriers.